Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and a rotor hub having one or more rotor blades connected thereto. The rotor blades capture kinetic energy of wind using known airfoil principles. Further, the rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to the gearbox, or if the gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
Various components of a wind turbine are typically housed within the nacelle. For example, the rotor hub may be coupled to a shaft extending within the nacelle. Further, the gearbox and the generator are typically coupled to the shaft and may be housed within the nacelle. A typical nacelle may include a frame structure having a base, side support walls, and top support members. A plurality of shell panels may be attached to the frame structure to enclose the nacelle. Alternatively, the nacelle may be constructed of a plurality of shell members manufactured using common molding processes such that the frame structure is eliminated.
In addition, the shell members may be manufactured to include a sandwich-panel configuration. Sandwich-structured panels generally include two thin but stiff sheets of material attached to a lightweight but thick core. The manufactured shell members may then be bolted or glued together to form the shell of the nacelle.
It is known in the art to mount and/or bolt sandwich panels together in a variety of ways. For example, one known method includes mounting a top or roof panel to the side panels via one or more L-flanges. The L-flanges, however, require the use of mold inlays during the infusion molding process and therefore increase manufacturing time, expense, and material usage. In addition, the L-flanges protrude within the nacelle, thereby taking up more space.
Another known method for joining the shell panels of the nacelle includes drilling holes into the manufactured sandwich panels and then installing steel plates having welded-on threaded rods. Such sandwich panels are manufactured using resin transfer molding (RTM). Once installed, the threaded rod extends within the nacelle and is free to slide around to a degree until a joining plate and bolts are coupled on the joining sandwich panel. Such joints are sometimes referred to in the art as “Jupiter joints”. Like the L-flange joints, Jupiter joints are also labor-intensive and costly and their threaded rods extend within the nacelle, which increase the likelihood of injury. In addition, Jupiter joints are associated with high material costs and require welding to ensure connection reliability between the plate and the threaded rod.
Accordingly, a nacelle having an improved joint design for a sandwich panel would be advantageous. For example, a nacelle having internal connection elements incorporated within the sandwich panels before the panels are molded would be desired.